Delphinium plant named ‘Tessa’

ABSTRACT

A new and distinct cultivar of  Delphinium  plant named ‘Tessa’, particularly distinguished by semi-double, deep blue-colored flowers, short, sturdy stems, narrow upright, vigorous growth habit, and very good mildew resistance with good garden performance, is disclosed.

Latin name of genus and species of plant claimed: Delphinium elatum.

Variety denomination: ‘Tessa’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar ofDelphinium plant botanically known as Delphinium elatum and hereinafterreferred to by the cultivar name ‘Tessa’. The new Delphinium cultivar isa naturally-occurring whole plant mutation. The new cultivar wasdiscovered and selected as a single plant within a population ofDelphinium elatum plants during 2005 in an outdoor nursery location inAbbenes, The Netherlands.

Asexual reproduction of the new Delphinium by vegetative cuttings anddivisions in a controlled environment in Abbenes, The Netherlands since2006, has shown that the unique features of the Delphinium are stableand have reproduced true-to-type in successive generations.

SUMMARY OF THE INVENTION

The following are the most outstanding and distinguishingcharacteristics of this new cultivar when grown under normalhorticultural practices in Abbenes, The Netherlands:

-   -   1. Semi-double, deep blue-colored flowers;    -   2. Short, sturdy stems;    -   3. Narrow upright, vigorous growth habit; and    -   4. Very good mildew resistance with good garden performance.

Of the many commercially available Delphinium cultivars, the mostsimilar in comparison to the new cultivar is ‘Darwin's Blue Indulgence’,U.S. Plant Pat. No. 13,011. However, in comparison, plants of the newcultivar ‘Tessa’ differ from plants of ‘Darwin's Blue Indulgence’ in atleast the following characteristics:

-   -   1. Plants of the new cultivar have a flower color that is darker        than plants of ‘Darwin's Blue Indulgence’;    -   2. Plants of the new cultivar have a semi-double flower form        that is different from the full-double flower form of plants of        ‘Darwin's Blue Indulgence’; and    -   3. Plants of the new cultivar are more resistant to mildew than        plants of ‘Darwin's Blue Indulgence’.

In addition the new cultivar can be compared to the commerciallyavailable cultivar, ‘Darwin's Pink Indulgence’, U.S. Plant Pat. No.13,065. However, in comparison, plants of the new cultivar ‘Tessa’differ from plants of ‘Darwin's Pink Indulgence’ in at least thefollowing characteristics:

-   -   4. Plants of the new cultivar have a flower color that is        different from plants of ‘Darwin's Pink Indulgence’;    -   5. Plants of the new cultivar have a semi-double flower form        that is different from the full-double flower form of plants of        ‘Darwin's Pink Indulgence’; and    -   6. Plants of the new cultivar are more resistant to mildew than        plants of ‘Darwin's Pink Indulgence’.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying photographs show, as nearly true as it is reasonablypossible to make the same in color illustrations of this type, typicalflower and foliage characteristics of the new cultivar. Colors in thephotographs differ slightly from the color values cited in the detaileddescription, which accurately describes the colors of ‘Tessa’. The plantwas field grown for approximately 1 year in Abbenes, The Netherlands inan outdoor nursery location. The plant was transplanted into a containerfor photography purposes.

FIG. 1 illustrates a side view of the overall growth and flowering habitof ‘Tessa’.

FIG. 2 illustrates a close-up view of an individual inflorescence of‘Tessa’.

FIG. 3 illustrates a close-up view of the foliage of ‘Tessa’.

DETAILED BOTANICAL DESCRIPTION

The new cultivar has not been observed under all possible environmentalconditions to date. Accordingly, it is possible that the phenotype mayvary somewhat with variations in the environment, such as temperature,light intensity, and day length, without, however, any variance ingenotype.

The chart used in the identification of colors described herein is TheR.H.S. Colour Chart of The Royal Horticultural Society, London, England,2007 edition, except where general color terms of ordinary significanceare used. The data which define these characteristics were collectedfrom asexual reproductions carried out in Abbenes, The Netherlands. Theplant history was taken in June 2011 on 1-year-old field grown plantswhich were planted and grown outdoors in daytime temperatures between14° C. and 28° C. and nighttime temperatures between 5° C. and 18° C. Nopinching, growth retardants or photoperiodic treatments were used.Observations were made when the plants were in natural daylightconditions.

-   Botanical classification: Delphinium elatum cultivar ‘Tessa’.-   Parentage:    -   -   Female parent.—Unknown Delphinium elatum.        -   Male parent.—Unknown Delphinium elatum.-   Propagation:    -   -   Type cutting.—Vegetative cutting.        -   Time to initiate roots.—Approximately 14 days with average            soil temperature of 20° C.        -   Time to produce a rooted cutting.—Approximately 40 days with            average soil temperature of 20° C.        -   Root description.—Grey, thin, fibrous, moderately dense.        -   Rooting habit.—Freely branching.-   Plant description:    -   -   Type.—Herbaceous perennial. Overall shape: Narrow triangle.            High temperature tolerance: Tolerant to at least 35° C. Low            temperature tolerance: Hardy to at least USDA Zone 4.            Excellent garden performance.        -   Commercial crop time.—After rooting, approximately 30 weeks            are required to produce a finished flowering plant in a            2-liter container.        -   Growth habit and general appearance.—Narrow upright,            vigorous.        -   Size.—Height from soil level to top of plant plane:            Approximately 105.0 cm. Width: Approximately 39.3 cm. Rate            of growth: In spring, approximately 20 cm per month.        -   Branching habit.—Non-branched; flowering stems grow from            base.        -   Stem.—Shape: Rounded, slightly angled. Strength: Very            strong. Aspect: Erect. Length to base of inflorescence:            Approximately 48.0 cm. Diameter: Approximately 1.3 cm.            Length of central internode: Approximately 2.2 cm. Texture:            Glabrous with a densely pubescent base, dull. Color of            pubescence: 157D. Color of young and mature stems: 146D with            stripes of 146A, glaucous layer of 145C.-   Foliage description:    -   -   General description.—Quantity of leaves per stem:            Approximately 22. Form: Simple. Arrangement: Alternate.            Durability to stress: Moderately high.        -   Leaves.—Shape: Palmately lobed. Margin: Incised. Apex:            Acute. Base: Hastate, not overlapping. Venation pattern:            Palmate. Length of mature leaf: Approximately 15.5 cm. Width            of mature leaf: Approximately 17.7 cm. Texture of upper            surface: Smooth, glabrous. Texture of lower surface:            Moderately pubescent on margins and venation. Color of            pubescence: 157D. Color of upper surface of young foliage:            137A with venation of 144B. Color of lower surface of young            and mature foliage: 138B with venation of 144C. Color of            upper surface of mature foliage: 137A to 137B with venation            of 144B.        -   Petiole.—Shape: Flattened. Length: Approximately 10.1 cm.            Width: Approximately 4.0 mm. Height: Approximately 3.0 mm.            Color: 144A.-   Flowering description:    -   -   Flowering habit.—Freely flowering under outdoor growing            conditions from early to mid-summer.        -   Lastingness of flower on the plant.—Approximately 10 to 14            days.-   Inflorescence description:    -   -   General description.—Type: Terminal raceme. Fragrance: None            detected. Height: Approximately 59.0 cm. Width:            Approximately 27.8 cm. Quantity of flowers and buds per            inflorescence: Approximately 45 for central inflorescence            and 17 for secondary inflorescences. Quantity of fully-open            flowers per inflorescence: Approximately 28 for central            inflorescence and 0 for secondary inflorescences.        -   Peduncle.—Strength: Very strong. Aspect: Erect primary            peduncles with secondary peduncles at approximately a 40°            angle. Length of primary: Approximately 56.8 cm. Diameter of            primary: Approximately 6.0 mm. Texture: Glabrous, smooth.            Color: 146D with stripes of 146A, glaucous layer of 145C.-   Flower description:    -   -   General description.—Type: Semi-double, self-cleaning.            Shape: Round, somewhat flattened. Aspect: Outward.        -   Bud just before opening.—Shape: Obovate, upper half tapers            to a spur. Length excluding spur: Approximately 1.4 cm.            Length of spur: Approximately 9.0 mm. Diameter:            Approximately 9.0 mm. Color: 122C with 188B and an underside            of 145C to 145D. Rate of opening: Approximately 10 days.        -   Corolla.—Arrangement: Whorls of outer and inner sepals and a            central whorl of petaloids. Depth (including spur):            Approximately 4.6 cm. Diameter: Approximately 7.3 cm.        -   Inner sepals.—Quantity: Approximately 8. Arrangement:            Rotate. Appearance: Velvety. Shape: Elliptic to obovate.            Margin: Entire to deeply incised. Apex: Broadly acute.            Length: Approximately 3.6 cm. Width: Approximately 2.0 cm.            Texture of upper and lower surfaces: Smooth, glabrous. Color            of upper surface when first open: 96D tinged with N88D, and            base of 138D. Color lower surface when first open: 96C and            base of 138D. Color of upper surface when fully open: 100A            with centers of 91A and base of 138C. Color lower surface            when fully open: 96C and 69D, base of 138D.        -   Petaloids.—Arrangement: Central whorl. Quantity:            Approximately 7. Shape: Spatulate, one is spurred. Length:            Approximately 1.7 cm. Width: Approximately 6.0 mm. Texture:            Center pubescence of short hairs having a length of            approximately 0.3 mm and color of 156D. Color: 203A with            base of 201B to 201D. Length of spur: Approximately 9.0 mm.            Width of spur: Approximately 2.0 mm. Color of spur: 147A.        -   Calyx (outer sepals).—Shape: Rotate. Depth (including spur):            Approximately 4.0 cm. Diameter: Approximately 7.1 cm.            Quantity: 5. Appearance: Velvety. Shape: Ovate, with upper            sepal spurred. Margin: Entire. Apex: Broadly acute. Length:            Approximately 4.0 cm. Width: Approximately 2.5 cm. Length of            spur: Approximately 2.3 cm. Width of spur: Approximately            6.0 mm. Texture of upper and lower surfaces: Smooth,            glabrous. Color of upper surface when first open: 100A,            margins tinged with 92D, and base of 138D. Color lower            surface when first open: 96C with a small circle of 138B            near the apex, base of 138D, and spur of 94A to 94B. Color            of upper surface when fully open: 100A, margins tinged with            92C to 92D, apex tinged with 92A, and base of 138C. Color            lower surface when fully open: 96C and 69D with a small            circle of 138B near the apex, base of 138D, and spur of 94A            to 94B.        -   Pedicel.—Strength: Strong. Aspect: Approximately at a 35°            angle. Length: Approximately 7.9 cm. Diameter: Approximately            2.0 mm. Texture: Smooth, glabrous. Color: 143A.        -   Reproductive organs.—Androecium: Stamen quantity: 40 per            flower, basifixed. Anther shape: Kidney-shaped. Anther            length: Approximately 1.5 mm. Filament length: Approximately            8.0 mm. Anther color: 203A. Filament color: NN155D. Pollen            amount: Moderate. Pollen color: 156D. Gynoecium: Pistil            quantity: 4 per flower. Pistil length: Approximately 3.0 mm.            Stigma shape: Pointed. Stigma color: NN155D. Style length:            Approximately 2.5 mm. Style color: NN155D. Ovary color:            N189B.-   Seed and fruit production: Neither seed nor fruit production has    been observed.-   Disease and pest resistance: Good mildew resistance. No particular    resistance or susceptibility to other diseases or insects noted to    date.

What is claimed is:
 1. A new and distinct cultivar of Delphinium plantnamed ‘Tessa’, substantially as herein shown and described.